The mirror baryons are an irreproachable candidate for DM [1]}, [2]}. However, the other types of DM could also be present. For example, the mirror baryons could not comprise all of the DM in a galaxy [3]}. With an additional DM component, the DM density in the universe becomes
\(\Omega _{\rm DM} = \Omega _{b^{\prime }} + \Omega _{\rm add},\) 
